End effectors are the last element of a kinematic chain of transport apparatuses, e.g. robots. They are used e.g. for gripping or holding objects.
In the production of micro-structure components, e.g. in chip manufacturing, end effectors are usually used to hold substrates in order to move substrates between different process stations.
Within the scope of this invention, substrates include in particular wafers, such as semiconductor wafers or glass wafers, flexible substrates, wafers which are produced synthetically from chips and casting compound (reconstituted wafers; moulded wafers with embedded dies) or substrates having 3-dimensional surfaces.
Such end effectors are known and usually consist of a main body having e.g. a milled vacuum channel and a cover which closes the vacuum channel. Suction can be applied to the wafer and it can be held by means of vacuum technology through openings in the cover. However, by reason of their construction, such end effectors are thick and troublesome to produce.
The wafers to be picked up by the end effector are frequently disposed in a wafer cartridge. In order to remove individual wafers from the wafer cartridge, the end effector is first moved between two wafers in the cartridge and is moved or brought into connection with one of the wafers in order to fix said wafer, e.g. by means of a vacuum or by means of excess pressure using the Bernoulli effect.
In order to accommodate the largest possible number of wafers in a wafer cartridge, the wafers are frequently disposed at a very small spacing from one another. Furthermore, wafers can be flexible and can sag when disposed horizontally, whereby the spacing between the wafers can be further reduced. The end effector must then also be able to be guided reliably between the wafers without contacting wafers e.g. on the “end face” and thereby damaging them.